It is known that such ventilating air intake arrangements are widely used in the aeronautical field for the purposes of replacing the air in a confined zone containing heat-sensitive equipment and/or hazardous ambient locations, of the inflammable or detonating type, for which it is necessary to provide continuous ventilation of the zone in order to prevent any risk of malfunction of the equipment or of nearby incident.
Such is the case in particular with many mechanical and/or electrical devices provided in the annular confined space or zone between the nacelle and the outer casing of the fan and the compressors of an aircraft turbojet. These devices, such as, for example, the fadec (full authority digital engine control), the gearbox, the engine oil tank, the fluidic components, etc., usually attached all around the outer casing and thus situated in the confined zone, are ventilated by outside air entering the arrangement via the air intake orifice to pass through the duct made in the nacelle and to diffuse, at the exit of the duct, in the confined zone. These devices, like the oil or other vapors emanating from this space, are ventilated by cool outside air diffused by the air duct, which helps to ensure that they operate correctly.
To satisfy the applicable regulation, which requires an appropriate rate of air replacement per unit of time of the confined zone in question, the air duct of the arrangement has a predetermined cross section allowing a sufficient quantity of air to circulate in the duct to ensure, at its exit, the replacement of air of the confined zone containing the devices to be ventilated.
However, the cooling devices and the vapors to be expelled are not ventilated optimally by the known air intake arrangements.
Specifically, in these arrangements, if the outside air entering upstream via the air intake orifice into the duct with a predetermined cross section of the arrangement and exiting downstream of the latter is sufficient to properly ventilate the devices when the aircraft is in the taxiing phase, in the take-off phase or in the holding phase, hence at low speed, on the other hand, when the aircraft is in the flight cruising phase at a maximum speed and altitude, the quantity of air or the flow of air exiting the duct of the arrangement toward the zone to be ventilated is too great. For this reason, the devices are overcooled because the temperature of the outside air is extremely low at this cruising altitude, which may lead to malfunctions. Furthermore, measures have made it possible to establish that, in this flight phase, the air circulating in the confined zone via the duct of the arrangement was replaced twice more than necessary, such that the fadec, in particular, is overcooled, which may impair its proper operation.
The object of the present invention is to remedy these disadvantages, and relates to an air intake arrangement whose design makes it possible to provide an optimal ventilation of a confined zone such as the one hereinabove of a turbojet, but which may also be a lights zone or a belly fairing zone or, in a general manner, any zone more or less enclosed and heat sensitive of a vehicle for which air replacement is desired.